This invention relates generally to satellite communications systems.
The satellite communications industry has experienced significant performance enhancements in the last few decades. Some examples of these performance enhancements include an increase in transmission power capability of satellite transponders, improvements in low-noise amplifier (LNA) characteristics, and a decrease in the size of receiving antennas. In satellite systems with a large number of receiving stations, it is particularly important to reduce the cost of each receiving unit and to design a system with a small receiving antenna to meet installation and aesthetic requirements. The need for a small receiving antenna has motivated an increase in transponder power output in order to maintain an acceptable signal-to-noise ratio (SNR) with the smaller antenna. As a result of these performance enhancements that boosted the popularity of small receiving antenna-high power transponder combination, the cost of low power transponders dropped significantly. However, many satellite users cannot take advantage of this economically efficient option because the bandwidth necessary to provide full featured programming is distributed among multiple low power transponders.
Attempts to overcome this problem include channel splitting, which includes splitting the original signal into subchannel signals, transmitting the subchannel signals through satellite transponders, and later recombining the subchannel signals so that the end user receives a reconstructed version of the original signal. Channel splitting, however, does not solve the problem of only a limited bandwidth being available for each subchannel. The limited bandwidth necessitates acquiring extra satellite capacity to transmit all the data, and the cost of developing extra satellite capacity might cancel out any cost saving associated with using a low power transponder. In order to make the use of the low power transponder an economically practical option, a way of using low power transponders and small receiving antennas without developing extra satellite capacity is needed.